Improvement in drill-gages



UNITED STATES PATENT OFFICE ALVAH C. TRAFTON, OF WORCESTER, MASSACHUSETTS.

IMPROVEMEN'I, IN DRILL-GAGES.

Specification forming part of nLetters Patent No. 139,487, dated June 3, 1873 application filed March 10, 1873. i

To all whom it may concern:

Be it known that I, ALVAH C. TRAFTON, of Worcester, in the county of Worcester and the Commonwealth of Massachusetts, have invented certain Improvements in DrillGages, of which the following is a speciiication:

`This invention relates to the production, as a new article of manufacture, of an improved gage for assisting mechanics in correctly grinding twist-drills.

In grinding twist-drills great difficulty is experienced in obtaining equally-beveled sides at the point, from the fact that it is necessary that the proper angle shall be given to the drill at the point, and that the sides shall be equally beveled, in order that the drill may run truly. It is almost impossible in practice to grind drills correctly by the eye alone, and even if the bevels are correctly obtained and the point is central, the angle at the point is often either too obtuse or too acute, and consequently the drill will not do its work as well and truly as if the same were ground correctly. In other cases, the bevels on the sides are frequently not alike, and the point is not central, in which case the drill will not cut properly, and will run to one side. From the fact of these diiculties constantly arising, few machinists are able to grind their own` drills properly, and, in consequence, a considerable prejudice has arisen against this tool, and in many cases machinists have f abandoned the use of the same, on'account of the great cost, arisingironij. the constant breaking of drills, owing tot-improper grinding and the difficulty and delay experienced inreplacing the same in many parts of the country. f

I am aware that attempts have been made to produce gages to assistineclranics in grinding drills; butin all cases such gages have been constructed with movable and adjustable guides, regulated by screws or other means, such parts having to be shifted for each size of drill ground; and, as a consequence, considerable experience is required before a mechanic can become so acquainted with the device as to use the same correctly.

'Ihe object of'my invention is to remedy these evils by producing a drill-gage the parts of which are al1 stationary, and so arranged that a drill of any'size below and including that of the maximum width of the centeringtrough may be centered andgaged by the same instrument with great accuracy without necessitating any experience ou the part of or otherwise connected. C D are two plates,

forming the gage. These plates C D are, by preference, arranged at an angle of one hundred and twenty degrees, (but this angle may be varied according to the requirements of the machinist,) and at E are firmly connected together by soldering or other suitable means, and at F they are provided with extensions `which are similarly aiixed to the sides A B of the trough. The plates C D are so affixed that the bevel of their respective faces shall be equal, and the line of their juncture F shall be perpendicular to and central with the line of the point of juncture of the plates A B.

By thus constructing drill-gages I obtain a permanent gage, and am able, by means of the trough A B, to center any size of drill, and, by means of the end gage, C D, to insure the "proper angle and equality of bevel, together with a perfectly central point. `It will also be found that the most inexperienced hands can use this gage with ease 'and accuracy.

Having thus described my invention, what l claim, and desire to secure by Letters Patent, is-

As a new article of manufacture, a drillgage, constructed with a centering-trough, composed of two plates, A B, connected together at right angles, and a bevel-regulating gage, composed of two plates, C D, connected together and permanently affixed to the centering-trough A B, substantially as shown, and for the purposes described.

ALVAH C. TRAFTON.

Witnesses:

JOSEPH B. GARDINER. NATHAN B. GooDNow. 

